Not Applicable.
1. Field of the Invention
This invention relates to custom-molded cushions, and is particularly well-adapted to custom-molded seating cushions designed for use with seated mobility systems such as wheelchairs.
2. Description of Related Art
Seated mobility platforms, wheelchairs and other seated mobility systems (hereinafter xe2x80x9cwheelchairsxe2x80x9d) provide a means of movement, positioning and postural support for persons with physical disabilities or deformities. These persons remain seated in or on the wheelchair, often in a fixed position, throughout most of their daily activities. Proper seating and positioning in the wheelchair is necessary to prevent pressure sores, to increase comfort and sitting tolerance, and to improve circulation, range of motion, respiratory function and digestion, all of which allow the user to achieve a higher degree of function and interaction with his or her environment.
Mass-produced wheelchair cushions, including inflatable cushions, jell pads and layered foam pads, are well known. Although mass-produced cushions are inexpensive and provide adequate support and positioning for some individuals, other persons require a padding system including contoured and form-fitting cushions. To such end, various types of custom-contoured wheelchair cushions, and methods for making such cushions, have been employed in an effort to form a seat that is xe2x80x9cmoldedxe2x80x9d to the shape of the portion of the user that contacts the wheelchair seat, i.e., the user""s xe2x80x9cseating surface.xe2x80x9d
For example, U.S. Pat. No. 4,615,856 discloses forming an impression of the user""s seating surface on a bead-filled bag and removing air from the bag to fix the impression. A positive mold of the individual""s impression is made from the bag, and is utilized to mold a customized seat cushion. In a similar method, the shape of the bead-filled bag is scanned into a computer which then cuts a cushion of the same shape out of a foam block. Although these methods are capable of creating fairly accurate and usable seating, the methods are labor intensive, take a considerable amount of time to complete and are expensive.
Another method for producing custom-contoured cushions is the foam-in-place method. In the foam-in-place method, a low density, high foaming two-part foam is mixed and poured into a flexible enclosure. As the foam begins expanding, the bag is placed on a simulator chair frame and the user is then positioned on the bag. The foam quickly expands around the user and cures with an imprint of the user on the cushion surface. The foam cushion is then covered with a suitable material to protect it from contaminants and moisture. The resultant cushion is very soft, but does not provide a great deal of support to the user.
Although the foam-in-place method can produce a cushion with a fairly accurate contoured surface, the speed at which the material foams and cures makes it difficult to mold the foam properly around the user. Further, the user can easily xe2x80x9cbottom outxe2x80x9d by displacing the uncured foam under the ischium, where it is needed most. Unfortunately, attempts to mold the foam around the user and work the foam under the ischium can cause tiny bubbles in the expanding foam to collapse, resulting in hard spots within the cushion. Poor mixing of the foam can also create inconsistent texture and density within the cushion, which can be uncomfortable to the user and cause pressure sores. Further, the expanding foam often leaks out of the bag creating a mess on the user, the cushion, the technician and the simulator chair.
Another method of customizing a cushion involves hand carving different densities of foam into pads of various shapes, which are then upholstered by traditional methods. Such customized cushions can be expensive to install and maintain and are generally less accurate than other customized cushions. The inaccuracy can result in pressure points that create soreness and discomfort for the user. Further, the external hardware required to position the pads is unsightly and, more importantly, may limit the user""s range of motion.
Although these known custom-contoured cushions are suitable for their intended purpose, a need remains for an inexpensive, easy to manufacture custom-contoured seat cushion that provides the comfort and support required by the intended user.
Thus, an object of the present invention is to provide a custom-contoured seat cushion that accurately conforms to the shape of the intended user""s seating surface and provides postural support to the user.
It is a further object of the present invention to provide such a custom-contoured cushion that is resilient and fairly soft.
Another object of the invention is to provide a method of making such a cushion that can be completed in one to two days.
It is yet another object of the invention to provide a custom-contoured cushion that has a uniform texture and density.
It is another object of the invention to provide an aesthetically pleasing custom-contoured cushion.
Yet another object of the present invention is to provide a high quality, low maintenance and durable cushion that is aesthetically pleasing.
The present invention is directed to a custom-contoured cushion for use as a seat bottom, seat back, headrest or other type of cushion for a wheelchair, or other seating device. The novel custom-contoured cushion is comprised of a stretchable bag having an opening that is in a closed position when the cushion is in use. The bag is filled with soft and non-absorbent pellets adhered together by and/or embedded within an elastomeric polymerizable adhesive, preferably a two-part low-foaming polyurethane adhesive. The pellets are sufficiently soft and resilient to provide a comfortable and durable cushion and are non-absorbent, so as not to absorb the adhesive, which could create inconsistencies in the texture and density of the cushion. In a preferred embodiment the cushion has been molded to conform to the shape of an object. Preferably, the cushion has been custom-molded to conform to the shape of the seating surface of an intended user.
The cushion may optionally include a baseboard to add structure and support to the cushion. Additional structure and support can be provided by generally L-shaped support guides, affixed along opposing edges of the baseboard. In one embodiment, the support guides are tall enough to obviate the need for separate modular hip and lateral support pads that are often added to wheelchairs. The baseboard and/or support guides may be affixed around the outside of the custom-contoured cushion or positioned within the cushion bag. In either embodiment, conventional wheelchair hardware may be mounted onto the baseboard to facilitate installation of the cushion onto the wheelchair or other support structure.
In an alternative embodiment, the cushion of the present invention does not contain an adhesive to adhere the pellets together. In such embodiment, the pellets are able to move relative to each other within the bag after construction is completed. Each time the user sits on the cushion, the pellets will deform to conform to the shape of the user""s seating surface. The user may purchase such a cushion xe2x80x9coff the shelfxe2x80x9d and use it with an existing chair for added comfort. Such xe2x80x9coff the shelfxe2x80x9d cushions will preferably be formed in appropriate dimensions to be used in standard sized chairs as can readily be calculated by one of skill in the art.
The custom-contoured cushion is preferably formed by custom molding. In a preferred custom molding process, a seating technician first measuring the user to determine the general dimensions required for the finished cushion. A bag conforming to such general dimensions is provided or constructed out of a suitable stretchable fabric. The bag is constructed with an opening through which the pellets, baseboard and support guides may be inserted. If a baseboard is to be included within the cushion, holes are drilled in the baseboard at locations appropriate for attaching hardware, and T-nuts are inserted into the holes. Support guides, if desired, are cut into the desired shape and affixed to the baseboard. The baseboard and support guides are then inserted into the bag, and the baseboard is positioned along the bottom of the bag.
A seating technician inserts the pellets into the bag, preferably until the bag begins to stretch, closes the opening, and places the bag on a simulator wheel-chair frame. The seating technician then places the intended user onto the bag to assess whether the bag contains a sufficient number of pellets to provide cushioning around the user""s seating surface and whether the baseboard and support guides are in the correct position to provide postural support. The seating technician may remove the user from the bag and make any needed adjustments to the bag and/or its contents. This process is repeated until the bag is properly filled and the support guides are positioned correctly.
The two-part adhesive is added to the pellets, and the pellets and adhesive are mixed until the adhesive is fully mixed and the pellets are uniformly coated. The adhesive and pellets can be mixed in the bag, after adding the mixed two-part adhesive to the pellets within the bag. Alternatively, before adding the adhesive, the technician may remove the pellets from the bag and transfer them into a mixing tub. The two-part adhesive is added to the tub and the pellets and adhesive are mixed. The pellet/adhesive mixture is then inserted into the bag and the opening is re-closed.
In either process, the filled bag is again placed on the simulator frame and the intended user is re-positioned on the bag. While the adhesive is curing, the technician molds the pellet/adhesive mixture contained in the bag around the user and between the user""s seating surface and any baseboard or support guides to provide cushioning around the seating surface, which results in a custom-molded cushion bearing an accurate impression of the seating surface. This may be done by pulling up on the bag and pushing the pellet/adhesive mixture into gaps between the user and the baseboard or support guides. During this process, the user may be removed from the cushion and the technician may push and/or pull the pellet/adhesive mixture into any spots where the user has bottomed out. The adhesive is then allowed to cure. Preferably the intended user remains on the cushion until the adhesive is cured.
When the adhesive has fully cured, approximately one hour from mixing, the cushion is complete and ready to be installed onto the wheelchair or other support structure. However, it may be desirable to modify the custom-molded cushion to add extra padding. For example, after curing, the technician or user may notice that additional pressure relief is needed at certain points. In such case, the technician may cut into the bag, pull the bag away from the pellet/adhesive mixture at the position that extra padding is needed and add a pad to the interior of the bag at the position that extra padding is needed. The hole in the bag may be patched with an additional piece of material from which the bag was cut, which piece may be affixed to the exterior of the bag, over the hole, with an adhesive. This patching material and method may also be used to repair damaged areas of the cushion after use by the user.
In one embodiment, prior to installing the cushion onto the wheelchair or other support structure, a cushion cover is added to the cushion. The cushion cover is preferably comprised of a terry cloth or fleece material cut and sewn into the shape of a sack that is slightly larger than the size of the cushion. The cushion cover preferably comprises a large opening, trimmed with an elastic band, zipper or other closure. The cushion cover is slipped over the cushion and held in place by the closure, which is preferably positioned on the underside of the cushion.
To install a cushion containing a baseboard, the technician first locates the T-nuts in the baseboard by feeling for the T-nuts through the bag. The aperture of a bracket is positioned against the exterior of the cushion, over the T-nut, and screws are inserted into the bracket aperture, through the bag and into the T-nut previously positioned within the board hole. The cushion can then be installed onto the wheelchair frame. If the baseboard is not present, the cushion may be affixed to a conventional wheelchair drop seat base or combined with other conventional hardware for installation onto the wheelchair or other support structure.
The molding process of the present invention produces an aesthetically pleasing custom-molded, custom-contoured cushion having a highly accurate impression of the intended user""s seating surface which substantially alleviates pressure points that can cause discomfort and pressure sores. The cushion has a uniform texture and density without the hard spots that can result from other molding procedures. The molding process does not significantly alter the flexible qualities of the foam pellets, such that they remain resilient and soft, and the adhesive is sufficiently flexible and resilient to provide a comfortable cushion for the user. Adding support guides produces a comfortable cushion that also provides necessary postural support and may obviate the need for additional cumbersome and unsightly hardware.
The molding process is relatively quick, such that the cushion can be molded and installed onto the wheelchair during a one-day session, and it does not result in the messes sometimes associated with other molding processes. Further, the cushion is adaptable to a variety of wheelchair frames or other support structures.